The present invention generally relates to system controllers for a network control system, and more particularly to a system controller which is adapted to control a system having a network with an open communication protocol via proprietary communication.
It is known in the control systems industry, especially the building control systems, to employ a control network to allow various system components to communicate with each other. Until recently, communication between the components in the network was through proprietary protocols developed by the control network developers/manufacturers. Increasingly, however, the control networks are now being implemented with open communication standards such as LonTalk® and BACnet. These communication protocols permit system components that are produced by different manufacturer to communicate with each other, thus providing the network designers the flexibility to choose system components from various sources.
Known control systems typically include one or more system controllers that are connected to device controllers that operatively control network devices. The system controller typically transmits commands to the device controllers for operating the network devices, and also receives data from the device controllers regarding status and other information about the network devices that may be of interest to the system controller for making decisions.
A problem associated with the known control system arrangements is that the communication between the system controller and the device controllers must be conducted via the open protocol of the system network. These protocols do not always have the capacity to provide the support necessary for implementing complex and increased functionalities required by some control systems such as a Heating/Ventilation/Air Conditioning (HVAC) system, for example. Known control system arrangements also limit designers' creativity in solving problems or expanding the capabilities of the system controller, because the designers are confined to the protocol of and the type of data provided by the network in place. Addition of new control applications to the control system is also complicated for the same reasons.